Illumination of pointers and dials of indicating instruments



y 15, 1953 cs. s. HUNTER ET AL 2,843,079

' ILLUMINATION 0F POINTERS AND DIALS OF INDICATING INSTRUMENTS OriginalFiled Oct. 16, 1951 3 Sheets-Sheet 1 IN VENTORS GORDON 5. HUNTER GEORGEC STURGES Arron/var July 15, 1958 G. S. ILLUMINATION OF POINTERS ANDDIALS OF INDICATING INSTRUMENTS Original Filed Oct. 16, 1951 3Sheets-Sheet 2 FIG. 2

1 /f 050%5 c. STURGES Air-away HUNTER ETAL 2,843,079

July 15, 1958 G. s. HUNTER ETAL 2,843,079

ILLUMINATION 0F POINTERS AND DIALS o v INDICATING INSTRUMENTS OriginalFiled Oct. 16, 1951 5 Sheets-Sheet 3 FIG. 3

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' II [Mm ii kww INVENTORS GORDON S. HUNTER GEORGE C. STURGES ATIDQ VEVliLLATION 01F PfiiNTERS AND DIALS F INDICATTNG INSTRUMENTS Gordon S.Hunter, Plainville, Conn., and George C.

Sturges, Bergenfield, N. 1., assignors to Bendix Aviation Corporation,Teterboro, N. J., a corporation of Delaware Continuation of applicationSerial No. 251,614, October 16, 1951. This application March 16, 1956,Serial No. 572,158

4 (Ilairns. (Cl. 116-129) This invention in general relates toindicating instruments and in particular to the illumination of thepointers and the dials of such instruments.

Previously in devices of this nature the position of the pointer againstthe dial was noted by silhouette, that is, the non-illuminated pointerWould eclipse the illuminated dial indicia and could thereby be located.An obvious disadvantage of this arrangement is that the occulted indiciaare not easily seen. On the other hand, with instruments in which themoving pointer is illuminated, the problem arises in piping theillumination into the moving pointer and in the provision of a uniformillumination intensity within the pointer.

The present invention therefore, contemplates an indicating instrumentwherein novel means are provided for effectively illuminating a dial anda movable lightconducting pointer. In order to utilize the light raysfrom a source of illumination for illuminating the lightconductingpointer and the indicia without a decrease in intensity thereof, a lighttransmitting plate having a portion of its surface coated withtranslucent paint is positioned adjacent a dial having engraved indicia.The painted surface of the plate acts as a diffuser of light to directlight rays into the dial so as to illuminate the indicia. One edge ofthe plate is provided with an arcuate and beveled surface which reflectslight rays, transmitted through the plate from the source ofillumination, into the bent portion of a movable pointer made ofcolorless transparent material. The underside of the pointer is paintedwith a light diffusing substance to simulate the object being positionedand indicated, and only this painted area and the indicia on the dialare visible to an observer under night-vision conditions.

An object of the present invention, therefore, is to provide novel meansfor effectively piping illumination into a movable pointer of anindicating instrument.

Another object is to provide novel means for illuminating the indicia ofa dial by employing the light diifusing surface of a light transmittingplate so as to utilize the radiant energy of the rays diffused Without alarge diminution in intensity.

A further object is to provide a light transmitting plate whichfunctions to illuminate the indicia of 'a dial and also serves to pipelight rays into a movable pointer.

Still another object is the provision of a light transmitting platehaving a beveled surface formed at one edge which is located adjacent abend in a movable pointer whereby high intensity illumination of thepointer is effected by piping of light rays into the pointer by thebeveled surface.

A further object is to provide novel means for illuminating the dial andpointers of indicating instruments.

The above and other objects and advantages of the present invention willappear more fully hereinafter from a consideration of the detaileddescription which follows taken together with the accompanying drawingswherein one embodiment of the invention is illustrated.

States Patent In the drawings, wherein like reference characters referto like parts throughout the several views;

Fig. 1 is a side elevational view, partly in section, of one form of anindicating instrument embodying the present invention;

Fig. 2 is a top plan View, in section, of the indicating instrument ofFig. 1 and showing in more detail the dial and pointer structure;

Fig. 3 is a front elevational view of the indicating instrument of Fig.1 and shows in particular the dial face and front of the pointer;

Fig. 4 is a diagrammatical representation of a portion of the lighttransmitting plate and the dial showing in particular the location ofthe light diffusing painted area on the plate with respect to theindicia carried by the dial;

Fig. 5 is a view of the underside of the movable pointer;

Fig. 6 is a top plan view of the light transmitting plate of the presentinvention; and

Fig. 7 is a section taken along line 77 of Fig. 6.

A problem arising with known types of illuminated instrument dial andpointer arrangements has been the inadequacy of proper illumination ofthe indicia on the dial and the pointer due to diminution in intensityof the light rays before the latter reach the surfaces to beilluminated. Frequently, these devices employed light transmitting rodsmounted in juxtaposition with a dial having engraved indicia and bothwere edge-lighted from the same source of illumination, the indiciabeing illuminated by light rays striking the engraved contours thereofwhile light rays entering the rods were internally reflected andtransmitted therethrough to illuminate a movable pointer. The difficultywith such arrangements is that the light rays entering the dial are nottotally reflected therein but rather they are partially refracted at thesurfaces of the dial thereby resulting in light rays of diminishedintensity reaching the indicia. Of course, this is unsatisfactory wherethe compartment in which the instrument is located is completelyblacked-out.

In the general form of the invention the indicating instrument isusually arranged upon an instrument board and comprises a signalreceiver connected to a signal transmitter which is actuated by themovement of an object, the position of which is to be reproduced andindicated by the instrument. It will be apparent that the instrumentembodying the present invention does not necessarily have to be aposition indicator but may indi cate any condition whatsoever.

Referring now more particularly to the drawings for a detaileddescription of one embodiment of the invention, Fig. 1 illustrates, byway of example, a position indicator having a substantially rectangularcasing 11 and a front cover 12. Mounted with casing 11 by suitablesupporting means generally designated by numeral 13, parts of which areshown in Figs. 1 and 2, is a signal receiver 14 electrically connectedto a signal transmitter (not shown) whereby signals developed at thetransmitter serve to angularly displace rotor shaft 16 of receiver 14. Apinion 17 is secured to the forward end of shaft 16 and is adapted formeshing engagement with a sector gear 19 (Fig. 2) mounted on arelatively short shaft 20 suitably journalled for rotation in bearings21 retained in a supporting member 22.

Supporting member 22 is provided with a pair of openings whichaccommodate a pair of light sockets 23 and lamps 24, one of the socketsand lamps only being shown in Figs. 1 and 2. Coincident with theopenings in member 22 are a pair of openings 25 formed in arectangularshaped light transmitting plate 26 (Fig. 6) which is securedback to back with member 22 by screws (not shown). Plate 26 is made of acolorless transparent material such as an acrylic resin highly polishedon all sides and has formed at one edge thereof an arcuate 45 bevel 27(Fig. 7) which is located as to be concentric With short shaft 20 (Fig.2). Light from lamps 24 will therefore be transmitted through the bodyof plate 26 and refiected externally of the plate by bevel 27. A portion29 of the surface of plate 26 which contacts member 22 is provided witha translucent coating such as white paint (the thickness of which isexaggerated in Fig. 4), the painted portion taking the form shown inbroken lines in Fig. 3. The translucent coating serves to intercept partof the light rays transmitted through the body of plate 26, and inaddition, reflects them toward the opposite surface of the plateimmediately above the painted portion so that rays pass out through thesurface and into the dial and through the indicia to illuminate theindicia.

A dial 30, made of colorless transparent material such as acrylic resin,is located adjacent to and in front of plate 26 and may be secured tothe face of plate 26 by screws (not shown) and is provided with indicia31 such as graduations and numerals distributed in the arc of a circle,such indicia being rendered capable of illumination by rendering thebackground opaque and the indicia translucent so as to be illuminated bylight directed into the body of the dial. The face of the dial isengraved and then uniformly sprayed with a translucent coating. Acoating of black paint or printers ink is then applied to the face ofthe dial by rolling in order to avoid coating the engraved indicia. Thearea containing or covered by indicia 31 is substantially equal to thearea covered by painted portion 29 on plate 26, and the latter isdirectly behind the indicia. In this manner, the light rays reflected byportion 29 transmitted externally of plate 26 enter the body of dial 30to illuminate indicia 31 with light rays of substantially highintensity. Since lamps 24 are located relatively close to paintedportion 29, very little diminution in intensity of the light rays iseffected inasmuch as the rays do not travel far before being interceptedby the painted portionj Movable relative to dial 30 is an indicatorassembly 35 which comprises an indicator or pointer 36, of the samematerial as plate 26 and dial 30, having highly polished surfaces.Pointer 36 has fastened at its bifurcated end a glare shield cover 37which in turn is secured to short shaft 20 by sleeve 38 and nut 40 (Fig.2). Shield 37 is fastened to two legs 41 (Fig. forming part of thebifurcated end of pointer 36, by screws 42 (Fig. 3). Pointer 36, at itsinner end, also has an inwardly bent portion 43 which passesintermediate legs 41 and terminates immediately adjacent bevel 27 ofplate 26, the sloping surface of the bevel facing away from the bentportion. Part of the underside of the pointer is coated with translucentpaint 44 and simulates the control surface of a mobile craft. Thus, whenpointer 36 is angularly displaced from zero the observer will be able tovisualize the actual position of the control surface in relation to thecraft and the amount of displacement from a zero or normally centeredposition. Dial 30 is formed adjacent shield 37 such that clearance isprovided between the dial and a wall 45 of the shield when it rotateswith shaft 26, the shield itself serving to prevent stray light from thebevel of plate 26 from entering the eyes of an observer. The positionalrelationship between bevel 27 and bent portion 43 of pointer 36 providesfor reflection of light rays, striking the bevel, externally of plate 26and into the pointer to illuminate the latter. Under blacked-outconditions, only the coated portion of pointer 36 will be visible to anobserver since the pointer is highly polished on all surfaces and onlythose light rays which strike the coated portion will be reflected intothe eyes of an observer. Under day-light conditions, the coated portion44 of pointer 36 will be readily seen because the black coating on dial30 will appear through the transparent portions of the pointer so as topresent.

a black background for coated portion 44.

In order to facilitate the insertion and the removal of lamps 24 thereis provided in dial 30 a pair of openings which accommodate internallythreaded bushings 46. A pair of caps 47 (Fig. 2) externally threaded forengagement with bushings 46 are provided so that access may be had tothe lamps. It has been found in practice that under blacked-outconditions instruments which are illuminated with red light are morepleasing to the eye and for that reason a red color screen 49 is securedto the caps to enclose lamps 24 when the caps are fully screwed in. Toprevent stray light, which may escape from around the edges of the dial,from reaching the eyes of an observer a bezel 50 is provided which issecured to the back of front cover 12. It is to be noted that a flangedportion 51 of the bezel defines the sides of an opening which is smallerthan dial 30. A transparent cover glass 52 is secured to cover 12 forpermitting visual access to the dial and for preventing foreign matterfrom entering inside the casing.

From the foregoing, it is apparent that the present invention providesnovel means for illuminating the indicia of a dial and a movable pointerof an indicating instrument without a diminution in intensity of lightrays. The utilization of a common light transmitting member or plate forilluminating both the indicia and the pointer effects an etficient andcompact lighting arrangement which provides for high intensityillumination. This application is a continuation-in-Whole of ourcopending application Serial No. 251,614, filed October 16, 1951.

Although one embodiment of the invention has been illustrated anddescribed in detail, it is to be expressly understood that the inventionis not limited thereto. Various changes can be made in the design andarrangement of the parts without departing from the spirit and scope ofthe invention as the same will now be understood by those skilled in theart.

We claim:

1. In an indicating device, a dial having an opaque portion withlight-conducting indicia therein, an indicator of light-conductingmaterial cooperating with said dial, a source of illumination, and alight transmitting member adapted to receive light rays from said sourceof illumination, said member having a first portion adapted to directlight rays received from said source directly from said member into saiddial and through said light conducting indicia to illuminate saidindicia and a second portion for directing other light rays receivedfrom said source into said indicator to illuminate the indicator.

2. In an indicating device, a dial having a body portion and an opaqueportion with light-conducting indicia therein, a transparent indicatormovable relative to the indicia and having a curved integrallight-conducting bend portion extending toward the back of said dial, alighttransmitting member mounted behind said dial to receive light froma light source and having the characteristic of piping lighttherethrough, and a light-reflecting curved surface formed on saidmember adjacent said indicator for transmitting into said bend portionof the indicator substantially the same quantity of light for eachposition of said indicator to illuminate said indicator, said memberhaving light diffusing means for intercepting and directing other lightrays externally of said member into the body portion of the dial forilluminating said indicia.

3. In an indicating device, a dial having indicia thereon, a source ofillumination, a light-conducting member disposed behind said dial andreceiving light rays from said source of illumination, said memberhaving a curved integral beveled surface for reflecting received lightrays externally of said member, a movable indicator of lightconductingmaterial disposed in front of said dial to cooperate with said indicia,said indicator having a lightconducting curved portion extending towardthe rear of said dial and terminating adjacent'said beveled surface forreceiving at each position of said indicator substantial- 15 the samequantity of light rays reflected from said beveled surface to illuminatesaid indicator.

4. In an indicating device, a dial having indicia thereon, alight-conducting plate disposed behind said dial, light source means forpassing light into said plate in directions generally parallel to thefront and back surfaces of said plate so that light is transmittedthrough said plate by multiple internal reflections, said plate havingan arcuate beveled surface extending between the front and back surfacesof the plate for reflecting part of the light transmitted therein outthrough the front of the plate in a generally arcuate field ofdistribution, and a light-conducting indicator mounted for rotation infront of said dial to cooperate with said indicia, said indicator havinga light-conducting curved portion extending toward the References Citedin the file of this patent UNITED STATES PATENTS 2,278,520 Klein Apr. 7,1942 2,287,605 Dickson June 23, 1942 FOREIGN PATENTS 214,644 SwitzerlandAug. 1, 1941 730,231 Great Britain May 18, 1955 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No. 2,843,079

July 15, 1958 Gordon 5. Hunter et a1.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 6, line 6, for 'portions" re'ad e positions Signed and sealedthis 7th day of October 1958.

(SEAL) I Attest:

KARL Ho AXLINE ROBERT C. WATSON Attesting Officer Commissioner ofPatents

